Rotary pumps and motors



4, 1966 H. D. FANSHAWE ROTARY PUMPS AND MOTORS 2 Sheets-Sheet 1 Filed001.- 9. 1964 [NVEVTOR H D. FAN SHAWE .BY C d/nwm, 7(M/m Oct. 4, 1966 H.D. FANSHAWE 3,276,336

' ROTARY PUMPS AND MOTORS Filed Oct. 9, 1964 2 Sheets-Sheet 2 H llFANfiHAWE di /2,071 W 95%3270 United States Patent 3,276,386 ROTARY PUMPSAND MOTORS Hew Dalrymple Fanshawe, Edinburgh, Scotland, assignor toENRD. Limited, London, England, a British compan Filed Oct. 9, 1964,Ser. No. 402,805 Claims priority, application Great Britain, Oct. 11,1963, 40,248/63 9 Claims. (Cl. 103-123) This invention relates to rotarypumps and motors and particularly relates to pumps and motors of thekind in which a rotor unit or a stator unit is shaped to provide two ormore compartments which are, in effect, swept by one or more vanes whichact between the rotor and stator units and slide in one of the units,leakage from one compartment to the or an adjacent compartment, alongthe space between the rotor and stator units, being limited by suitablychosen close clearances between the rotor and stator units at thoseparts.

It is obvious that the rotor and stator units should not undergo toomuch strain under the pressurised conditions in which the pump or motoris to operate since, otherwise, the clearances referred to would beincreased and excessive leakage would occur; adequate limitation ofleakage under operating conditions is normally secured by suitabledimensioning and/or by choice of materials to prevent undue strainand/or distortion under the maximum pressure conditions. The higher thepressure, and/or the greater the length of wall swept by the vanes ineach compartment, the thicker, for instance, will the wall of the outermember (normally the stator) need to be. For very high pressures,however, if the same materials were to be used as for lower pressureoperation, the wall would have to be made so thick that the overall sizeof the device would become inordinately great and possibly, for certainpurposes, unmanageable. Even though materials of higher modulus wereavailable, the increase in modulus could not be great and the materialswould be far more costly and their use would probably be ruled out foreconomic reasons.

It is an object of the present invention to provide for reduction ofminimum thickness of the outer of the units of such pumps or motors fora given operating pressure or, alternatively, to provide a means forenabling such devices to be designed to work under reasonable conditionsof leakage at higher pressure, without the necessity for excessiveincrease of bulk or for inordinate increase in cost.

In accordance with the present invention, the outer unit (which willnormally be the stator unit) of a pump or motor of the kind refererd to,is arranged to be subjected to fluid pressurisation, and in this wayradial swelling of the outer unit, under the operating pressure, willtend to be counteracted. As an example of putting the invention intoeffect, the wall thickness of the outer unit of an existing design ofpump or motor could be retained at its minimum value while the operatingpressure could be raised considerably by such subjection topressurisation, the actual increase depending to an extent upon thedegree of pressurisation effected. Conversely, yet on a similar basis,it could be arranged that the thickness of the normal outer unit of aknown device for comparatively low pressure operation could be reducedfor the same operating pressure. In an arrangement according to theinvention, enveloping means needs to be provided, against which thepressurised fluid may react, and this may take the form of a simpleannulus of suitable material; the limitation on radial strain of theenveloping means is not related to leakage clearances, but only to theelastic limit of the material of which it is formed and the requiredpressurisation.

Patented Oct. 4, 1966 The pressurisation effected may be to a fixedvalue, but it is probable that adjustable pressurisation may be of usein particular cases; in certain embodiments, the pressurisation may beequal to, or related to, the operating pressure of the pump or motor. Itmay be desirable to pressurise so as to cause radial contraction of theouter unit, to compensate for the radial contraction of the inner unitunder operating pressure, and so maintain the close clearances betweenrotor and stator.

One embodiment of the invention will now be described by way of examplewith reference to the accompanying drawings of which FIGURE 1 is apart'sectional side elevation of a double-unit motor; FIGURE 2 is anelevation of one of the units indicating that each unit oomprises sixvanes acting between a cylindrical stator unit and the rotor unit thatare arranged to cooperate to form eight fluid compartments; FIGURE 3 isa part-sectional half elevation of one of the units of the motor andFIG- URE 4 is a part-sectional view at right-angles to the line AA inFIGURE 1.

In the drawings, the stators 1 and 2 of the two parts are arranged to beclamped together by end manifolds with suitable bolts, and a sandwichpiece 3 is arranged between them; dowels 4 are provided to spigot thestators and the sandwich piece, tension in the bolts being, for example,such as to avoid leakage of fluid under maximum operating pressureconditions of the motor. The eight fluid compartments of each unit ofthe motor are formed between lobes of the contoured part 5 of the rotor,and such lobes are indicated at 6; the contoured part is fitted andkeyed to the driving shaft 7 of the motor. The sandwich piece has a borewhich clears this part of the shaft.

The sandwich piece is provided with eight plug units, these fittingeight cut-outs 9 (FIGURES l and 4) which correspond in position withkeyhole-shaped slots 11 in the stators, each slot 11 housing a slidingvane 12 and providing a space 10 behind each vane.

Supported within each cut-out 9 is a pivot 13 for a rocker arm 14, theends of which are arranged to bear upon the outer edges of the vanes 12in both parts so that, when the motor is functioning, the inner edges ofthe vanes are biased into contact with the edge of the contoured part ofthe rotor. Initially, biasing pressure is obtained from the forceexerted on the pivot 13 by springs guided by plungers 15 which slide inbearings 17; once powered rotation is established, additional hydraulicbiasing pressure is obtained from pressurised fluid which is bled fromthe high pressure compartment on one side of each vane to the spaces 10at the backs of the vanes. This bleed occurs naturally up the highpressure face of each vane, due to the attitude it adopts in its slotwhen under load.

On each side of each vane slot 11 are ports 19 and 20. For clockwiserotation of the shaft, ports 19 are input (pressure) ports forpressurised fluid fed from supply passages 21 communicating with inputmanifold, and ports 20 are exhaust ports to exhaust the fluid frombehind the vanes as the pressurised fluid reacts on the front of thevanes to rotate the rotor; for this clockwise rotation, the exhaustfluid is led through passages 22 to the outlet manifold. The rotor andvanes are omitted from FIGURE 2 for clarity. Interchange of fluidconnections to the rnanifolds will reverse the rotation of the rotor.

The rotor of the other part of the motor is keyed to the shaft 7 so thatits lobes and vanes are exactly oppositely positioned relative to thoseof the first part, a typical positioning being indicated in dottedoutline relative to the vane and lobe on the line B-B of FIGURE 2,though in actual practice, the vanes are in a common plane through theline B-B. The sandwich piece 3 is provided with aligned passages so thatthe pressure ports and exhaust ports respectively of each part 5 are incommunication with each other, and therefore with the respective inputand exhaust manifold.

By reason of the relative displacement of the rotors referred to above,and appropriate shaping of the lobes, the combined volume of theportions of the compartments being swept at any instant by associatedvanes remains substantially constant and the torque and speed of themotor remains substantially constant during each revolution, providedthat there is a constant supply of fluid.

The stators 1, which are of comparatively light construc tion, would besubject to distortion under pressure of fluid in the various sweptcompartments, thereby leading to the clearances between the tops of thelobe portions of the rotors and the inner surfaces of the stators beingincreased in operation and, in consequence, leading to excessive leakagepast the lobes. However, in order to avoid this, in accordance with theinvention each stator is surrounded by a ring member 2, each beingsealed to the sandwich piece 3 by an O-ring seal 23 and to therespective manifold by similar means.

The internal dimensions of the ring 2 are such that, while permittingeasy tolerances for machining, the ring will readily fit over itsassociated stator, leaving a reasonable clearance 24. Passages 18 areprovided in the sandwich piece and in the plug units in cut-outs 9 sothat pressurised fluid that bleeds to the spaces 10 behind the vaneswill communicate with the space 24 to pressurise it, substantially atthe operating pressure of the actuating fluid of the motor.

This fluid pressure acting on the outside periphery of each stator byreaction with the pressure ring 2, more than balances the high pressureforces on its inside surface, and so causes an inner contraction of thestator to compensate for any contraction of the associated rotor,thereby preserving the clearances between rotors and stators. It will beseen that, even if the rings themselves expand, this is of noconsequence to operation of the motor. A high degree of strain beingacceptable therefore, the pressure rings may be highly stressed, so thatthey can usefully be made of stronger material than the stators andcomparatively thinly in consequence. The overall size of the motor forhigh pressure operation may be appreciably smaller than if the statorsthemselves were to be of the thickness required to resist unduedistortion under such operating pressures; thus the stator material maybe a spheroidal graphite iron which has properties suitable to impartwear resistance to its surface, and the pressure rings may be suitablymachined from a high tensile steel.

It will be observed that the pressure rings 2 need not be rigidly fixedto provide for uniformity of the clearance space 24, since the fluidpressure acting in this space will not be affected by its shape.

Alternatively, the space 24 may be pressurised from an independentsource of pressure. For this purpose further O-ring, or like, sealswould be required to be between each stator and the sandwich piece onone side and the appropriate manifold on the other; a suitable ductwould need also to be provided, probably in each manifold, through whichpressurised fluid could be led to the clearance spaces 24. The actualpressure required to minimise clearances between stator and rotor beingrelated to precise form and strength of the stator under the operatingpressure.

It will be appreciated that similar consideration-s would apply in thecase of a pump.

I claim:

1. A rotary hydraulic device comprising a stator unit, a rotor unit,said rotor unit being arranged to cooperate with said stator unit toprovide at least two compartments for hydraulic fluid, at least one vanemember adapted to bridge the gap between said stator and rotor units andin effect to sweep said compartments as the rotor unit rotates, anenveloping member peripherally surrounding and spaced from 111. Outer ofsaid stator and rotor units and arranged for substantially free movementrelative to said stator unit in directions at right angles to the axisof rotation of the rotor unit, and means for supplying hydraulic fluidunder pressure to the space between said enveloping member and the outerof said units to compensate for pressure within said outer unit.

2. A rotary hydraulic device as claimed in claim 1, wherein said rotorand stator units are made from material of comparatively low tensilestrength and said enveloping member is made from material having hightensile strength.

3. A rotary hydraulic device as claimed in claim 2, wherein said rotorand stator units are of cast iron and said developing member is of hightensile steel.

4. A rotary hydraulic device comprising a stator unit and rotor unitcombination, said stator unit surrounding said rotor unit, and saidrotor unit being arranged to cooperate with said stator unit to provideat least two compartments for hydraulic fluid, at least one vane memberadapted to bridge the gap between said stator and rotor units and ineffect to sweep said compartments as the rot-or unit rotates, a shaftfor said rotor unit, an enveloping member surrounding said stator unitand rotor unit combination, end members arranged one on either sideaxially of said stator unit and rotor unit combination, means forsecuring said end members and said stator unit in rigid fluid-tightassembly, at least one of said end members having bearing means forrotatably supporting said rotor unit shaft, said enveloping member beingarranged at least in part between said end members, and fluid pressuresealing means arranged between the sides of said enveloping member andsaid end members.

5. A rotary hydraulic device as claimed in claim 4, wherein said sealingmeans comprise O-ring members each contacting said enveloping member andone of said end members.

6. A rotary hydraulic device comprising at least one casing member, astator unit rigid with and in fluid-tight connection with said casingmember, a rotor unit, at least one rotor unit bearing in said casingmember, said rotor unit being arranged to cooperate with said statorunit to provide at least two compartments for hydraulic fluid at leastone vane member adapted to bridge the gap between said stator and rotorunits and in effect to sweep said compartments as the rotor unitrotates, said stator unit cooperating with said casing member to provideat least one fluid entry passage and at least one fluid outlet passagefor said compartments, said entry passage and said outlet passage beingon opposite sides of said vane member, an enveloping member peripherallysurrounding and spaced from the outer of said stator and rotor units,and at least one sealing means on each side of said enveloping memberbetween the enveloping member and the casing member, said sealing meansbeing under the influence of forces substantially only in the directionof the axis of rotation of said rotor unit and said enveloping memberbeing substantially free from restraint in directions at right angles tosaid axis, the arrangement being such that fluid contained by saidsealing means within the space between the enveloping member and theouter of said units react against the outer of said units to compensatefor pressure within said outer unit.

7. A rotary hydraulic device comprising a pair of rotor units, a shaftfor said rotor units, a stator unit for each said rotor unitperipherally surrounding the rotor unit, a spacer member between saidstator units, two end casing members, each said casing member havingbearing means for said rotor unit shaft, clamping means clamping each ofsaid stator units between a casing member and said spacer member inrigid fluid-tight assembly, one of said casing members having hydraulicfluid entry means and said other casing member having hydraulic fluidoutlet means, fluid passages in each of said stator units communicatingwith said fluid entry means and said fluid outlet means, each pair ofrotor and stator units being arranged to cooperate to provide at leasttwo compartments for fluid, at least one vane member for each said pairof units adapted to bridge the gap between the units of each pair and ineffect to sweep the said compartments as the rotor unit rotates, saidvane member being arranged between the fluid entry passage and the fluidoutlet passage in the respective stator unit, an enveloping memberperipherally surrounding and spaced from each stator unit and beingarranged at least in part between one casing member and the spacermember, and at least one sealing means on each side of each saidenveloping member, said sealing means being arranged between theenveloping member and the respective casing member and between theenveloping member and the spacer member, said sealing means being underthe influence of forces substantially only in the direction of the axisof rotation of said shaft and each said enveloping member being therebysubstantially free from restraint in directions at right angles to saidaxis, the arrangement being such that fluid contained by said sealingmeans within the space between each enveloping member and the respectivestator unit reacts against said stator unit to compensate for pressureWithin said stator unit while leaving the enveloping membersubstantially free for movement in directions at right angles to saidaxis.

8. A rotary hydraulic device comprising two stator units and a rotorunit for each of said stator units, said rotor units being arranged tocombine with the respective stator unit to provide at least twocompartments for hydraulic fluid in each combination, at least one vanemember in each combination, a vane slot in one unit of each saidcombination, said vane members being adapted to act to bridge the gapsbetween the repective two units in each combination and in effect tosweep the compartments in the same as each rotor unit rotates, asandwich member between said two stator units, said sandwich memberbeing provided with means for mechanically biasing said vane membersagainst the rotor surface, manifold end means at each end of the device,said manifold means being clamped with the stator units and sandwichmember between them, in rigid fluid tight assembly, enveloping meansenveloping each said stator unit, said enveloping means being adapted tocontain pressurising fluid to cause pressure to be exerted upon theouter surfaces of said stator units to counteract, at least in part, anytendency of said stator unit to swell under pressure of hydraulic fluidin said compartments, and pressure resisting sealing means between eachsaid enveloping means and surfaces adjoining said enveloping means toassist in containing said pressurising fluid, said enveloping meansbeing substantially free from restraint in directions at right angles tothe axes of rotation of said rotor units.

9. A rotary hydraulic device as claimed in claim 8, wherein a passage isprovided between said sandwich member and one of said stator units toprovide access from said vane slot to the space between each saidenveloping means and its associated stator unit, whereby saidpressurising fluid may be derived from the hydraulic fluid in saidcompartments.

References Cited by the Examiner UNITED STATES PATENTS 763,525 6/1904Van Beresteyn 103-123 1,460,487 7/1923 Hawkins 103-136 2,373,457 4/1945Chisholm 103--123 2,713,828 7/1955 Huber 103-123 2,918,877 12/1959Woodcock 103-136 2,974,603 3/1961 Fraser 103-121 3,011,449 12/1961 Ernst103-121 MARTIN P. SCHWADRON, Primary Examiner. WILBUR J. GOODLIN,Examiner.

1. A ROTARY HYDRAULIC DEVICE COMPRISING A STATOR UNIT, A ROTOR UNIT,SAID ROTOR UNIT BEING ARRANGED TO COOPERATE WITH SAID STATOR UNIT TOPROVIDE AT LEAST TWO COMPARTMENTS FOR HYDRAULIC FLUID, AT LEAST ONE VANEMEMBER ADAPTED TO BRIDGE THE GAP BETWEEN STATOR AND ROTOR UNITS AND INEFFECTS TO SWEEP SAID COMPARTMENTS AS THE ROTOR UNIT ROTATES, ANEVELOPING MEMBER PERIPHERALLY SURROUNDING AND SPACED FROM THE OUTER OFSAID STATOR AND ROTOR UNITS AND ARRANGED FOR SUBSTANTIALLY FREE MOVEMENTRELATIVE TO SAID STATOR UNIT IN DIRECTIONS AT RIGHT ANGLES TO THE AXISOF ROTATION OF THE ROTOR UNIT, AND MEANS FOR SUPPLYING HYDRAULIC FLUIDUNDER PRESSURE TO THE SPACE BETWEEN SAID ENVELOPING MEMBER AND THE OUTEROF SAID UNITS TO COMPENSATE FOR PRESSURE WITHIN SAID OUTER UNIT..